Lithium-stuffed garnet thin films and pellets having an oxyfluorinated and/or fluorinated surface and methods of making and using the thin films and pellets

ABSTRACT

Set forth herein are processes for making lithium-stuffed garnet oxides (e.g., Li 7 La 3 Zr 2 O 12 , also known as LLZO) that have passivated surfaces comprising a fluorinate and/or an oxyfluorinate species. These surfaces resist the formation of oxides, carbonates, hydroxides, peroxides, and organics that spontaneously form on LLZO surfaces under ambient conditions. Also set forth herein are new materials made by these processes.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 62/582,303, filed Nov. 6, 2018, and titledLITHIUM-STUFFED GARNET THIN FILMS AND PELLETS HAVING AN OXYFLUORINATEDAND/OR FLUORINATED SURFACE AND METHODS OF MAKING AND USING THE THINFILMS AND PELLETS, the entire contents of which are herein incorporatedby reference in its entirety for all purposes.

BACKGROUND

Conventional rechargeable batteries use liquid electrolytes tophysically separate and thereby electrically insulate the positive andnegative electrodes (i.e., cathodes and anodes, respectively). However,liquid electrolytes suffer from several problems including flammabilityduring thermal runaway, outgassing at high voltages, and chemicalincompatibility with lithium metal negative electrodes. As analternative, solid electrolytes have been proposed for next generationrechargeable batteries. For example, Li⁺ ion-conducting ceramic oxides,such as lithium-stuffed garnets (e.g., Li₃La₇Zr₂O₁₂, aka LLZO), havebeen considered as electrolyte separators. See, for example, US PatentApplication Publication No. 2015/0099190, published Apr. 9, 2015, andfiled Oct. 7, 2014, titled GARNET MATERIALS FOR LI SECONDARY BATTERIESAND METHODS OF MAKING AND USING GARNET MATERIALS; U.S. Pat. Nos.8,658,317; 8,092,941; and 7,901,658; also US Patent ApplicationPublication Nos. 2011/0281175; 2013/0085055; 2014/0093785; and2014/0170504; also Bonderer, et al. “Free-Standing Ultrathin CeramicFoils,” Journal of the American Ceramic Society, 2010, 93(11):3624-3631;and Murugan, et al., Angew Chem. Int. Ed. 2007, 46, 7778-7781), theentire contents of each of these publications are incorporated byreference in their entirety for all purposes.

When LLZO is sintered (e.g., US Patent Application Publication No.2016/0087321 to Wohrle, et al.) and subsequently exposed to ambientconditions (room temperature, natural atmosphere, e.g., 78% N₂ & 21% O₂;and/or with moisture also present), the surface of LLZO is contaminatedwith surface species which may negatively affect Li⁺ ion-conductivity.For example, lithium carbonate (Li₂CO₃) spontaneously forms on LLZOsurfaces when exposed to ambient conditions. The mechanism of lithiumcarbonate formation on LLZO when exposed to ambient conditions is known.For example, see Cheng, L., et al., “Interrelationships among GrainSize, Surface Composition, Air Stability, and Interfacial Resistance ofAl-Substituted Li₇La₃Zr₂O₁₂ Solid Electrolytes,” ACS Appl. Mater.Interfaces, 2015, 7 (32), pp 17649-17655, which discloses that LLZO canform Li₂CO₃ via two pathways: the first pathway involves a reaction withmoisture in air to form LiOH, which subsequently reacts with CO₂ to formLi₂CO₃; and the second pathway involves direct reaction between LLZO andCO₂. See also Cheng, L., et al., Phys. Chem. Chem. Phys., 2014, 16,18294-18300, which discloses that Li₂CO₃ was formed on the surface whenLLZO pellets were exposed to air. Lithium carbonate as well as otherforms of surface contamination, e.g., oxides, carbonates or organics,may negatively affect the electrochemical performance of a solidelectrolyte in an electrochemical device by increasing the interfacialimpedance between the LLZO solid electrolyte and other electrochemicaldevice components. Previous solutions, e.g., U.S. Pat. No. 9,966,630 B2,which issued May 8, 2018 and is titled ANNEALED GARNET ELECTROLYTESEPARATORS, the entire contents of which are herein incorporated byreference in its entirety for all purposes, include using an annealingstep to remove surface species that negatively affect electrochemicalperformance. However, improvements are still needed.

There is therefore a need for processes for decreasing the interfacialresistance of LLZO thin film solid electrolytes by passivating the LLZOsurface, with respect to surface reactions that result in surfacecontaminants that negatively affect Li⁺ ion conductivity, as well asprocesses for removing these surface contaminants. New materials made bythese processes are also needed. The instant disclosure sets forthsolutions to these problems as well as other unmet needs in the relevantart.

SUMMARY

In one embodiment, set forth herein is a process, including thefollowing steps (1) providing a solution including a fluoride salt and asolvent; (2) providing a sintered lithium-stuffed garnet thin film orpellet; (3) immersing at least one surface of the sinteredlithium-stuffed garnet thin film or pellet in the solution at atemperature between, or equal to, 0° C. and 60° C.; and (4) removing theat least one surface of the sintered lithium-stuffed garnet thin filmfrom the solution. In some examples, the process is performed in theorder in which the steps are recited.

In a second embodiment, set forth herein is a sintered lithium-stuffedgarnet thin film or pellet, wherein the thin film or the pellet includesa top surface and bottom surface and a bulk therebetween, wherein thetop surface or bottom surface, or both, include fluorine, and whereinthe fluorine is incorporated into, or bonded to, the lithium-stuffedgarnet.

In a third embodiment, set forth herein is a sintered lithium-stuffedgarnet thin film made by a process set forth herein.

In a fourth embodiment, set forth herein is a method, including thefollowing steps providing a sintered lithium-stuffed garnet thin film orpellet set forth herein; exposing the sintered thin film lithium-stuffedgarnet thin film or pellet to ambient conditions; and measuring the ASRof the sintered thin film lithium-stuffed garnet; wherein the sinteredlithium-stuffed garnet thin film or pellet includes: a top surface andbottom surface and a bulk therebetween, wherein the top surface orbottom surface, or both, comprise fluorine; wherein the fluorine isincorporated into, or bonded to, the lithium-stuffed garnet.

In a fifth embodiment, set forth herein is an electrochemical deviceincluding a sintered thin film lithium-stuffed garnet thin film orpellet prepared by a process set forth herein or a sintered thin filmlithium-stuffed garnet thin film or pellet set forth herein.

In a sixth embodiment, set forth herein is an electric vehicle includingan electrochemical device set forth herein, a sintered lithium-stuffedgarnet thin film or pellet prepared by a process set forth herein, or asintered lithium-stuffed garnet thin film or pellet set forth herein.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 shows X-ray photoelectron spectroscopy (XPS) results for thesintered thin films described in Example 1: (a) Non-soaked controlsintered thin films, (b) sintered thin films soaked in an electrolyticsolution mixture of ethylene carbonate and sulfolane (ECS) and thelithium salt, LiPF₆, (c) sintered thin films soaked in an electrolyticsolution mixture of SCN and the lithium salt, LiBF₄, and (d) sinteredthin films soaked in an electrolytic solution mixture of two dinitrilesolvents and the lithium salt, LiBF₄ electrolytic solution.

FIG. 2 shows X-ray photoelectron spectroscopy (XPS) results for thesintered thin films described in Example 2. The plot shows the relativeamount of CO₃ present, with respect to Zr present, at the surface of alithium-stuffed garnet sintered thin film as a function of the exposuretime.

FIG. 3 shows ASR of a full cell using the soaked garnet as a function ofrest voltage.

FIG. 4 shows a plot of atom percentages for F, Zr, and O as a functionof depth of penetration as measured by x-ray photoelectron spectroscopy(XPS).

FIG. 5 shows the chemical shifts in a Fluorine-19 solid-state nuclearmagnetic resonance (NMR) spectroscopy measurement as described inExample 5.

FIG. 6 shows an illustration of an electrochemical cell made and testedin Example 3.

DETAILED DESCRIPTION

The following description is presented to enable one of ordinary skillin the art to make and use the invention and to incorporate it in thecontext of particular applications. Various modifications, as well as avariety of uses in different applications will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to a wide range of embodiments. Thus, the inventions hereinare not intended to be limited to the embodiments presented, but are tobe accorded their widest scope consistent with the principles and novelfeatures disclosed herein.

All the features disclosed in this specification, (including anyaccompanying claims, abstract, and drawings) may be replaced byalternative features serving the same, equivalent or similar purpose,unless expressly stated otherwise. Thus, unless expressly statedotherwise, each feature disclosed is one example only of a genericseries of equivalent or similar features.

Please note, if used, the labels left, right, front, back, top, bottom,forward, reverse, clockwise and counter clockwise have been used forconvenience purposes only and are not intended to imply any particularfixed direction. Instead, they are used to reflect relative locationsand/or directions between various portions of an object.

I. General

The instant disclosure set forth processes that include simple,industrial scalable low temperature steps, which are carried out at atemperature lower than 60° C. and which enhance the interfacial propertyof a lithium-stuffed garnet thin film electrolyte thin film or pelletseparator. As a result of the processes set forth herein, alithium-stuffed garnet surface that is free, or has a trace fraction, oflithium carbonate is formed. The lithium-stuffed garnet surface formed(i.e., treated or modified) by the processes, herein, has a fluorinatedor oxyfluorinated surface.

The invention disclosed herein uses certain types of organic electrolytesolutions to clean the surface of garnet-type solid electrolyte. Agarnet thin film electrolyte is either soaked before assembly into abattery or directly used as is in the cell assembly using the organicelectrolyte. As the result of the contact between the liquid electrolyteand garnet surface, surface Li₂CO₃ is etched away and garnet solidelectrolyte surface is exposed. The exposed garnet surface isfluorinated or oxyfluorinated and shows improved stability in ambientenvironments for at least up to 3 days. The treated lithium-stuffedgarnets described herein maintain a low area-specific resistance (ASR).

The processes set forth herein include, but are not limited to, (1) aprocess that removes the Li₂CO₃ from lithium-stuffed garnet; (2) aprocess that provides a fluorinated surface including Li—Zr—La—Al—O—F onlithium-stuffed garnet; and (3) a process that provides anoxyfluorinated surface including Li—Zr—La—Al—O—F on lithium-stuffedgarnet.

The processes set forth herein not only remove Li₂CO₃ fromlithium-stuffed garnet, but these processes also provide stablelithium-stuffed garnet surfaces that inhibit or slow the rate offormation of Li₂CO₃ when the surfaces are exposed to ambient conditions.

II. Definitions

As used herein, the term “about,” when qualifying a number, e.g., 15%w/w, refers to the number qualified and optionally the numbers includedin a range about that qualified number that includes±10% of the number.For example, about 15 w/w includes 15% w/w as well as 13.5% w/w, 14%w/w, 14.5% w/w, 15.5% w/w, 16% w/w, or 16.5% w/w. For example, “about75° C.,” includes 75° C. as well 68° C., 69° C., 70° C., 71° C., 72° C.,73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C., 80° C., 81° C.,82° C., or 83° C.

As used herein, the phrase “ambient conditions,” refers to roomtemperature and a natural atmosphere such as the atmosphere of planetEarth that includes approximately 78% N₂ & 21% O₂; and/or with moisturealso present. Ambient conditions include standard temperature andpressure, with a relative humidity of at least 1%.

As used herein, the term “annealing” refers to a process wherein asintered electrolyte thin film is heated from 200° C. to 1000° C. in areducing atmosphere such as but not limited to Argon, hydrogen, or acombination thereof. Example anneal processes are described in U.S. Pat.No. 9,966,630 B2, which issued May 8, 2018 and is titled ANNEALED GARNETELECTROLYTE SEPARATORS, the entire contents of which are hereinincorporated by reference in its entirety for all purposes.

As used herein, the phrase “at least one member selected from the group”includes a single member from the group, more than one member from thegroup, or a combination of members from the group. At least one memberselected from the group consisting of A, B, and C includes, for example,A, only, B, only, or C, only, as well as A and B as well as A and C aswell as B and C as well as A, B, and C or any combination of A, B, andC.

As used herein, the term “ASR” refers to area specific resistance.

As used herein, the term “bulk” refers to a portion or part of amaterial that is extended in space in three-dimensions by at least 1micron (μm). The bulk refers to the portion or part of a material whichis exclusive of its surface, as defined below. The bulk portion of alithium-stuffed garnet thin film or pellet, which has a fluorinated oroxyfluorinated surface, is the interior portion of the thin film orpellet which is not fluorinated or oxyfluorinated. Whether a portion ofthe thin film or pellet is fluorinated or oxyfluorinated is determinedby whether fluoride or oxyfluoride species are detectable by XPS in theportion. The bulk of a thin film or pellet is also characterized as theportion of the thin film or pellet which is not at the surface of thethin film or pellet and which is therefore not exposed at the surface ofthe thin film or pellet.

As used herein, the term “contaminant” refers to a chemical deviationfrom a pristine material. A contaminant in a lithium-stuffed garnet mayinclude any material other than lithium-stuffed garnet such as, but notlimited to, a lithium carbonate, a lithium hydroxide, a lithium oxide, alithium peroxide, a hydrate thereof, an oxide thereof, or a combinationthereof, wherein oxide and lithium oxide do not include alithium-stuffed garnet. Contaminants of a garnet may include, but arenot limited to, hydroxides, peroxides, oxides, carbonates, andcombination thereof, which are not lithium-stuffed garnet.

As used herein, the term “drying” refers to a process of evaporating asolvent or a solution from a material such as a thin film or a pellet.Drying can be passive wherein a thin film or pellet is dried where it isstored by allowing the solvent or solution to evaporate. Drying can beactive wherein a thin film or pellet is heated to drive off a solvent ora solution. Drying, storing, and heating may be performed in ambientconditions. Drying, storing, and heating may be performed in dry roomconditions. Drying, storing, and heating may be performed in glove boxconditions.

As used herein, the term “electrolyte” refers to an ionically conductiveand electrically insulating material. Electrolytes are useful forelectrically insulating the positive and negative electrodes of arechargeable battery while allowing for the conduction of ions, e.g.,Lit, through the electrolyte.

As used herein, the phrases “electrochemical cell” or “battery cell”shall, unless specified to the contrary, mean a single cell including apositive electrode and a negative electrode, which have ioniccommunication between the two using an electrolyte. In some embodiments,a battery or module includes multiple positive electrodes and/ormultiple negative electrodes enclosed in one container, i.e., stacks ofelectrochemical cells. A symmetric cell unless specified to the contraryis a cell having two Li metal anodes separated by a solid-stateelectrolyte.

As used herein the phrase “electrochemical stack,” refers to one or moreunits which each include at least a negative electrode (e.g., Li, LiC₆),a positive electrode (e.g., Li-nickel-manganese-oxide or FeF₃,optionally combined with a solid state electrolyte or a gelelectrolyte), and a solid electrolyte (e.g., lithium-stuffed garnetelectrolyte set forth herein) between and in contact with the positiveand negative electrodes. In some examples, between the solid electrolyteand the positive electrode, there is an additional layer comprising agel electrolyte. An electrochemical stack may include one of theseaforementioned units. An electrochemical stack may include several ofthese aforementioned units arranged in electrical communication (e.g.,serial or parallel electrical connection). In some examples, when theelectrochemical stack includes several units, the units are layered orlaminated together in a column. In some examples, when theelectrochemical stack includes several units, the units are layered orlaminated together in an array. In some examples, when theelectrochemical stack includes several units, the stacks are arrangedsuch that one negative electrode is shared with two or more positiveelectrodes. Alternatively, in some examples, when the electrochemicalstack includes several units, the stacks are arranged such that onepositive electrode is shared with two or more negative electrodes.Unless specified otherwise, an electrochemical stack includes onepositive electrode, one solid electrolyte, and one negative electrode,and optionally includes a gel electrolyte layer between the positiveelectrode and the solid electrolyte.

As used herein, the phrase “electrochemical device” refers to an energystorage device, such as, but not limited to a Li-secondary battery thatoperates or produces electricity or an electrical current by anelectrochemical reaction, e.g., a conversion chemistry reaction such as3Li+FeF₃↔3 LiF+Fe.

As used herein, the phrase “film” or “thin film” refers to a thinmembrane of less than 0.5 mm in thickness and greater than 10 nm inthickness. A thin film is also greater than 5 mm in a lateral dimension.A “film” or “thin-film” may be produced by a continuous process such astape-casting, slip casting, or screen-printing.

As used herein, the phrase “film thickness” refers to the distance, ormedian measured distance, between the top and bottom faces of a film. Asused herein, the top and bottom faces refer to the sides of the filmhaving the largest surface area. As used herein, thickness is measuredby cross-sectional scanning electron microscopy.

As used herein, the term “pellet” refers to a small unit of bulkymaterial compressed into any of several shapes and sizes, e.g.,cylindrical, rectangular, or spherical. The compressed material isdisc-shaped and may be 5-20 cm in diameter and 0.5 to 2 cm in height.Typically, the compressed material is disc-shaped and 10 cm in diameterand 1 cm in height. Pellets may also include additional agents to helpbind the material compressed into the pellet. In some examples, theseadditional agents are referred to as binding agents and may include, butare not limited to, polymers such as poly(ethylene)oxide. In someexamples, polyvinyl butyral is used as a binding agent. Pellets aretypically made by pressing a collection of powder materials in a press.This pressing makes the powder materials adhere to each other andincreases the density of the collection of powder material when comparedto the density of the collection of powder material before pressing. Insome instances, the powder material is heated and/or an electricalcurrent is passed through the powder material during the pressing.

As used herein, the term “pressed pellet” refers to a pellet having beensubmitted to a pressure (e.g., 5000 PSI) to further compress the pellet.

As used herein, the phrase “lithium-stuffed garnet” refers to oxidesthat are characterized by a crystal structure related to a garnetcrystal structure. Lithium-stuffed garnets include compounds having theformula Li_(A)La_(B)M′_(c)M″_(D)Zr_(E)O_(F), orLi_(A)La_(B)M′_(C)M″-_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, 0≤C≤2,0≤D≤2; 0≤E<2.5, 10<F<13, and M′ and M″ are each, independently in eachinstance selected from Al, Mo, W, Nb, Ga, Sb, Ca, Ba, Sr, Ce, Hf, Rb,and Ta; or Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f), wherein 5<a<7.7; 2<b<4;0<c≤2.5; 0≤d<2; 0≤e<2, 10<f<13 and Me″ is a metal selected from Nb, V,W, Mo, Ta, Ga, and Sb. Garnets, as used herein, also include thosegarnets described above that are doped with Al or Al₂O₃. Also, garnetsas used herein include, but are not limited to, Li_(x)La₃Zr₂O₁₂+yAl₂O₃,wherein x may be from 5.8 to 7.0, and y may be 0.1, 0.2, 0.3, 0.4, 0.5,0.6, 0.7, 0.8, 0.9, or 1.0. As used herein, garnet does not includeYAG-garnets (i.e., yttrium aluminum garnets, or, e.g., Y₃Al₅O₁₂). Asused herein, garnet does not include silicate-based garnets such aspyrope, almandine, spessartine, grossular, hessonite, or cinnamon-stone,tsavorite, uvarovite and andradite and the solid solutionspyrope-almandine-spessarite and uvarovite-grossular-andradite. Garnetsherein do not include nesosilicates having the general formulaX₃Y₂(SiO₄)₃ wherein X is Ca, Mg, Fe, and, or, Mn; and Y is Al, Fe, and,or, Cr.

As used herein, the phrase “lithium interfacial resistance” refers tothe interfacial resistance of a material towards the incorporation orconduction of Li⁺ ions. A lithium interfacial ASR (ASR_(interface)) iscalculated from the interfacial resistance (R_(interface)) viaASR_(interface)=R_(interface)*A/2 where A is the area of the electrodesin contact with the separator and the factor of 2 accounts for 2interfaces, assuming the cell is symmetric.

As used herein, the phrase “positive electrode” refers to the electrodein a secondary battery towards which positive ions, e.g., Li⁺, conductduring discharge of the battery. As used herein, the phrase “negativeelectrode” refers to the electrode in a secondary battery from wherepositive ions, e.g., Li⁺, conduct during discharge of the battery. In abattery comprised of a Li-metal electrode and a conversion chemistryelectrode (i.e., active material; e.g., NiF_(x)), the electrode havingthe conversion chemistry materials is referred to as the positiveelectrode. In some common usages, cathode is used in place of positiveelectrode, and anode is used in place of negative electrode. When aLi-secondary battery is charged, Li ions conduct from the positiveelectrode (e.g., NiF_(x)) towards the negative electrode (Li-metal).When a Li-secondary battery is discharged, Li ions conduct towards thepositive electrode (e.g., NiF_(x); i.e., cathode) and from the negativeelectrode (e.g., Li-metal; i.e., anode).

As used herein, the terms “separator” refers to a solid electrolytewhich conducts Li⁺ ions, is substantially insulating to electrons, andis suitable for use as a physical barrier or spacer between the positiveand negative electrodes in an electrochemical cell or a rechargeablebattery. A separator, as used herein, is substantially insulating toelectrons when the separator's lithium ion conductivity is at least 10³times, and typically 10⁶ times, greater than the separator's electronconductivity. Unless explicitly specified to the contrary, a separatoras used herein is stable when in contact with lithium metal.

As used herein, the term “surface” refers to a material, or portion of amaterial, that is near or at an interface between two different phases,chemicals, or states of matter. A surface is the area of contact betweentwo different phases or states of matter (e.g., solid-gas, liquid-gas,or solid-liquid). For example, the interface of two solids which are indirect contact with each other is a surface. For example, a thin filmgarnet separator when exposed to air has a surface described by theperiphery or outside portion of the separator which contacts the air.For rectangular-shaped separators, there is a top and a bottom surfacewhich both individually have higher total geometric surface areas thaneach of the four side surfaces individually. In this rectangular-shapedseparator example, there are four side surfaces which each havegeometric surface areas less than either of the top and bottom surfaces.For a disc-shaped separator, there is a top and a bottom surface whichboth individually have higher geometric surface areas than thecircumference-side of the disc-shaped separator. Geometric surface areais calculated for a square or rectangular shaped-surface by multiplyinglength of the surface by the width of the surface. Geometric surfacearea is calculated for disc-shaped surface by multiplying π by thesquared radius of the disc, i.e., πr² wherein r is the radius of thedisc surface. Geometric surface area is calculated for the side of adisc by multiplying the disc circumference by the width of the side ofthe disc. When used as an electrolyte in an electrochemical cell, eitherthe top or bottom surface is the surface of the separator which directlycontacts the negative electrode (e.g., Li metal), the positive electrode(i.e. cathode or catholyte in the cathode), and/or a layer or adhesivebonding agent disposed between the separator and the positive electrode.A surface is defined by an area that has larger, or more extended, x-and y-axis physical dimensions than it does z-axis physical dimensions,wherein the z-axis dimension is perpendicular to the surface. The depth,roughness or thickness of a surface can be of a molecular order (0.1 to10 nanometers) of magnitude or up to 1, 2, 3, 4, or 5 μm.

As used herein, the term “top and bottom surfaces” refer to the twosurfaces that have the largest total geometric surface area for amaterial having more than two surfaces. For example, a rectangle has sixsurfaces—four side surfaces and one top and one bottom surface. In sucha rectangle, there is one top and one bottom surface which are parallelto each other. In a rectangle, there are four side surfaces which areperpendicular to both the top and bottom surfaces. In a rectangle, thetop and bottom surfaces individually have a larger geometric surfacearea than the geometric surface area of each of the four side surfacesindividually.

As used herein, the phrase “fluorinated” refers to the presence of achemical species that includes fluorine or fluoride.

As used herein, the phrase “fluorinated surface” refers to a surface towhich fluoride is bonded or incorporated as determined by XPS or NMR.Unless specified explicitly otherwise, the fluorinated surface featureis determined by XPS.

As used herein, the phrase “oxyfluorinated” refers to the presence of achemical species that includes oxygen and fluorine or oxygen andfluoride.

As used herein, the phrase “oxyfluorinated surface” refers to a surfaceto which oxygen and fluorine is bonded or incorporated as determined byXPS or NMR. Unless specified explicitly otherwise, the oxyfluorinatedsurface feature is determined by XPS.

As used herein, the phrase “substantially free of” refers to thepresences of a chemical species below the XPS detectable limit. Forexample, a lithium-stuffed garnet that is substantially free of Li₂CO₃on its surface has Li₂CO₃ on the surface in an amount less than 1 atomic% measured by XPS. As used herein, the phrase “trace amounts ofcontaminants,” refers to the presences of a chemical species below theXPS detectable limit.

As used herein, the term “LiBETI” refers to lithiumbis(perfluoroethanesulfonyl)imide.

As used herein, the term “LiTFSI” refers to lithiumbis(trifluoromethane)sulfonimide.

As used herein, the term “LiFSI” refers lithiumbis(fluorosulfonyl)imide.

As used herein, the term “LIBOB” refers to lithium bis(oxalato)borate.

As used herein, the term “XPS” refers to X-ray photoelectronspectroscopy which is a surface-sensitive quantitative spectroscopictechnique that measures the elemental composition at the parts perthousand range. XPS is useful for determining the empirical formula ofan analyzed species. XPS is useful for determining the chemical stateand electronic state of the elements that exist within a material.

As used herein, the term “LLZO” refers to a lithium lanthanum zirconiumoxide, which when crystallized into the garnet crystal form is referredto as lithium-stuffed garnet as defined above.

As used herein, the term “GITT” refers to the Galvanostatic IntermittentTitration Technique.

As used herein, the term “EIS” refers to Electrochemical ImpedanceSpectroscopy.

As used herein, the term “ECS” refers to a mixture of ethylene carbonate(EC) and sulfolane. Sulfolane refers to tetrahydrothiophene 1,1-dioxide,having the cyclic sulfone structure shown below:

The ratio, EC:sulfolane, is 45:55 vol % unless specified to thecontrary. The ratio—EC:sulfolane—may range from 3:7 to 5:5 v/v, but isunderstood to be 45:55 vol % unless specified otherwise.

As used herein, the term “SCN” refers to succinonitrile.

III. Processes for Making Surface-Treated Lithium-Stuffed GarnetElectrolytes

In some examples, set forth herein is a process for making a sinteredlithium-stuffed garnet thin film or pellet having a treated surface,including (1) providing a solution including a fluoride salt and asolvent; (2) providing a sintered lithium-stuffed garnet thin film orpellet; (3) immersing at least one surface of the sinteredlithium-stuffed garnet thin film or pellet in the solution at atemperature between, or equal to, 0° C. and 60° C.; and (4) removing theat least one surface of the sintered lithium-stuffed garnet thin filmfrom the solution. In some examples, the process includes (2) providinga sintered lithium-stuffed garnet thin film. In some examples, theprocess includes (2) providing a sintered lithium-stuffed garnet pellet.In some examples, step (2) includes providing a sintered lithium-stuffedgarnet thin film or pellet which has a pristine surface including onlylithium-stuffed garnet, as determined by x-ray photoelectronspectroscopy. In some examples, the process includes (2) providing asintered lithium-stuffed garnet pellet. In some examples, step (2)includes providing a sintered lithium-stuffed garnet thin film or pelletwhich has an untreated surface. In some examples, step (2) includesproviding a sintered lithium-stuffed garnet thin film or pellet whichhas an annealed surface in which there is no detectable amount oflithium carbonate, lithium hydroxide, or lithium oxide on the surface,as detected by x-ray photoelectron spectroscopy. In some examples, thestep of removing the at least one surface of the sinteredlithium-stuffed garnet thin film from the solution yields a sinteredlithium-stuffed garnet thin film having a fluorinated or oxyfluorinatedsurface.

In some examples, set forth herein is a process for treating ormodifying a sintered lithium-stuffed garnet thin film or pellet having atreated surface, including (1) providing a solution including a fluoridesalt and a solvent; (2) providing a sintered lithium-stuffed garnet thinfilm or pellet; (3) immersing at least one surface of the sinteredlithium-stuffed garnet thin film or pellet in the solution at atemperature between, or equal to, 0° C. and 60° C.; and (4) removing theat least one surface of the sintered lithium-stuffed garnet thin filmfrom the solution. In some examples, the process includes (2) providinga sintered lithium-stuffed garnet thin film. In some examples, theprocess includes (2) providing an untreated sintered lithium-stuffedgarnet pellet.

In some examples, including any of the foregoing, the process furtherincludes drying the sintered lithium-stuffed garnet after step (3).

In some examples, including any of the foregoing, the process furtherincludes drying the sintered lithium-stuffed garnet after step (4).

In some examples, including any of the foregoing, the fluoride salt isselected from the group consisting of LiPF₆, lithiumbis(perfluoroethanesulfonyl)imide (LIBETI),bis(trifluoromethane)sulfonimide lithium salt (LiTFSI), LiBF₄, LiAsF₆,lithium bis(fluorosulfonyl)imide (LiFSI), LiAsF₆, and combinationsthereof.

In some examples, including any of the foregoing, the fluoride salt isLiPF₆.

In some examples, including any of the foregoing, the fluoride salt islithium bis(perfluoroethanesulfonyl)imide (LIBETI).

In some examples, including any of the foregoing, the fluoride salt isbis(trifluoromethane)sulfonimide lithium salt (LiTFSI).

In some examples, including any of the foregoing, the fluoride salt isLiBF₄.

In some examples, including any of the foregoing, the fluoride salt isLiAsF₆.

In some examples, including any of the foregoing, the fluoride salt islithium bis(fluorosulfonyl)imide (LiFSI).

In some examples, including any of the foregoing, the fluoride salt isLiBF₄ or LiPF₆.

In some examples, including any of the foregoing, the fluoride salt isLiBF₄ and LiPF₆.

In some examples, including any of the foregoing, the concentration offluoride salt in the solution is about 0.5 M to about 1.5 M. In someexamples, including any of the foregoing, the concentration is about 0.5M, about 0.55 M, about 0.6 M, about 0.65 M, about 0.7 M, about 0.75 M,about 0.8 M, about 0.85 M, about 0.9 M, about 0.95 M, about 1.0 M, about1.05, about 1.10, about 1.15, about 1.2, about 1.25, about 1.30, about1.35, about 1.4, about 1.45, or about 1.5 M.

In some examples, including any of the foregoing, the concentration offluoride salt in the solution is about 0.5 M to about 1.5 M. In someexamples, including any of the foregoing, the concentration is 0.5 M,0.55 M, 0.6 M, 0.65 M, 0.7 M, 0.75 M, 0.8 M, 0.85 M, 0.9 M, 0.95 M, 1.0M, 1.05, 1.10, 1.15, 1.2, 1.25, 1.30, 1.35, 1.4, 1.45, or 1.5 M.

In some examples, including any of the foregoing, the concentration offluoride salt in the solution is 0.5 M to 1.5 M. In some examples,including any of the foregoing, the concentration is 0.5 M, 0.55 M, 0.6M, 0.65 M, 0.7 M, 0.75 M, 0.8 M, 0.85 M, 0.9 M, 0.95 M, 1.0 M, 1.05,1.10, 1.15, 1.2, 1.25, 1.30, 1.35, 1.4, 1.45, or 1.5 M.

In some examples, including any of the foregoing, the concentration is0.5 M.

In some examples, including any of the foregoing, the concentration is0.55 M.

In some examples, including any of the foregoing, the concentration is0.6 M.

In some examples, including any of the foregoing, the concentration is0.65 M.

In some examples, including any of the foregoing, the concentration is0.7 M.

In some examples, including any of the foregoing, the concentration is0.75 M.

In some examples, including any of the foregoing, the concentration is0.8 M.

In some examples, including any of the foregoing, the concentration is0.85 M.

In some examples, including any of the foregoing, the concentration is0.9 M.

In some examples, including any of the foregoing, the concentration is0.95 M.

In some examples, including any of the foregoing, the concentration is1.5 M.

In some examples, including any of the foregoing, the concentration isabout 0.5 M.

In some examples, including any of the foregoing, the concentration isabout 0.55 M.

In some examples, including any of the foregoing, the concentration isabout 0.6 M.

In some examples, including any of the foregoing, the concentration isabout 0.65 M.

In some examples, including any of the foregoing, the concentration isabout 0.7 M.

In some examples, including any of the foregoing, the concentration isabout 0.75 M.

In some examples, including any of the foregoing, the concentration isabout 0.8 M.

In some examples, including any of the foregoing, the concentration isabout 0.85 M.

In some examples, including any of the foregoing, the concentration isabout 0.9 M.

In some examples, including any of the foregoing, the concentration isabout 0.95 M.

In some examples, including any of the foregoing, the concentration isabout 1.5 M.

In some examples, including any of the foregoing, the solvent isselected from the group consisting of ethylene carbonate (EC),diethylene carbonate, dimethyl carbonate (DMC), ethyl-methyl carbonate(EMC), propylmethyl carbonate, nitroethyl carbonate, propylene carbonate(PC), diethyl carbonate (DEC), methyl propyl carbonate (MPC),2,5-dioxahexanedioic acid dimethyl ester, tetrahydrofuran (THF),γ-butyrolactone (GBL), fluoroethylene carbonate (FEC), fluoromethylethylene carbonate (FMEC), trifluoroethyl methyl carbonate (F-EMC),fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), dioxolane,prop-1-ene-1,3-sultone (PES), sulfolane, acetonitrile (ACN),succinonitrile (SCN), pimelonitrile, suberonitrile, propionitrile,propanedinitrile, glutaronitrile (GLN), adiponitrile (ADN),hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, ethyl propionate, methyl propionate, methylenemethanedisulfonate, dimethyl sulfate, dimethyl sulfoxide (DMSO), ethylacetate, methyl butyrate, dimethyl ether (DME), diethyl ether,dioxolane, gamma butyl-lactone, methyl benzoate,2-methyl-5-oxooxolane-2-carbonitrile, and combinations thereof. In someexamples, the combinations of solvents are those combinations which aremiscible.

In some examples, including any of the foregoing, the solvent isethylene carbonate (EC).

In some examples, including any of the foregoing, the solvent isdiethylene carbonate.

In some examples, including any of the foregoing, the solvent isdimethyl carbonate (DMC).

In some examples, including any of the foregoing, the solvent isethyl-methyl carbonate (EMC).

In some examples, including any of the foregoing, the solvent ispropylmethyl carbonate.

In some examples, including any of the foregoing, the solvent isnitroethyl carbonate.

In some examples, including any of the foregoing, the solvent ispropylene carbonate (PC).

In some examples, including any of the foregoing, the solvent is diethylcarbonate (DEC).

In some examples, including any of the foregoing, the solvent is methylpropyl carbonate (MPC).

In some examples, including any of the foregoing, the solvent is2,5-dioxahexanedioic acid dimethyl ester.

In some examples, including any of the foregoing, the solvent istetrahydrofuran (THF).

In some examples, including any of the foregoing, the solvent isγ-butyrolactone (GBL).

In some examples, including any of the foregoing, the solvent isfluoroethylene carbonate (FEC).

In some examples, including any of the foregoing, the solvent isfluoromethyl ethylene carbonate (FMEC).

In some examples, including any of the foregoing, the solvent istrifluoroethyl methyl carbonate (F-EMC).

In some examples, including any of the foregoing, the solvent isfluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE).

In some examples, including any of the foregoing, the solvent isfluorinated cyclic carbonate (F-AEC).

In some examples, including any of the foregoing, the solvent isdioxolane.

In some examples, including any of the foregoing, the solvent isprop-1-ene-1,3-sultone (PES).

In some examples, including any of the foregoing, the solvent issulfolane.

In some examples, including any of the foregoing, the solvent isacetonitrile (ACN).

In some examples, including any of the foregoing, the solvent issuccinonitrile (SCN).

In some examples, including any of the foregoing, the solvent ispimelonitrile.

In some examples, including any of the foregoing, the solvent issuberonitrile.

In some examples, including any of the foregoing, the solvent ispropionitrile.

In some examples, including any of the foregoing, the solvent ispropanedinitrile.

In some examples, including any of the foregoing, the solvent isglutaronitrile (GLN).

In some examples, including any of the foregoing, the solvent isadiponitrile (ADN).

In some examples, including any of the foregoing, the solvent ishexanedinitrile.

In some examples, including any of the foregoing, the solvent ispentanedinitrile.

In some examples, including any of the foregoing, the solvent isacetophenone.

In some examples, including any of the foregoing, the solvent isisophorone.

In some examples, including any of the foregoing, the solvent isbenzonitrile.

In some examples, including any of the foregoing, the solvent is ethylpropionate.

In some examples, including any of the foregoing, the solvent is methylpropionate.

In some examples, including any of the foregoing, the solvent ismethylene methanedisulfonate.

In some examples, including any of the foregoing, the solvent isdimethyl sulfate. dimethyl sulfoxide (DMSO),

In some examples, including any of the foregoing, the solvent is ethylacetate.

In some examples, including any of the foregoing, the solvent is methylbutyrate.

In some examples, including any of the foregoing, the solvent isdimethyl ether (DME).

In some examples, including any of the foregoing, the solvent is diethylether.

In some examples, including any of the foregoing, the solvent isdioxolane.

In some examples, including any of the foregoing, the solvent is gammabutyl-lactone.

In some examples, including any of the foregoing, the solvent is methylbenzoate.

In some examples, including any of the foregoing, the solvent is2-methyl-5-oxooxolane-2-carbonitrile.

In some examples, including any of the foregoing, the solvent isselected from the group consisting of succinonitrile (SCN),glutaronitile (GLN), sulfolane, ethylene carbonate (EC), ethyl-methylcarbonate (EMC), and combinations thereof.

In some examples, including any of the foregoing, the solution is anysolution or electrolyte disclosed in US Patent Application PublicationNo. US20170331092A1, which published Nov. 16, 2017, titled as SOLIDELECTROLYTE SEPARATOR BONDING AGENT, the entire content of theapplication is incorporated by reference in its entirety for allpurposes.

In some examples, including any of the foregoing, the solvent is acombination of SCN and GLN. In some examples, including any of theforegoing, the GLN is about 57 wt % of the solvent combination. In someembodiments, GLN is about 55 wt % to 60 wt % of the solvent combination.

In some examples, including any of the foregoing, the solvent has awater content less than 200 ppm, or less than 150 ppm, or less than 100ppm, or less than 60 ppm, or less than 50 ppm, or less than 40 ppm, orless than 30 ppm, or less than 20 ppm, or less than 10 ppm. The watercontent of the solvent or the full electrolyte mixture moisture ismeasured by Karl Fischer coulometric titration, using a Mettler ToledoC20. The catholyte “Coulomat CG-K” and the anolyte “Hydranal AK” areused in the titration and the electrolyte is directly injected into thesystem for moisture analysis. Both catholyte and anolyte can bepurchased from Fluka.

In some examples, including any of the foregoing, the electrolytesolution is selected from those disclosed in US Patent ApplicationPublication No. US20170331092A1, which published Nov. 16, 2017, titledas SOLID ELECTROLYTE SEPARATOR BONDING AGENT, the entire content of theapplication is incorporated by reference in its entirety for allpurposes.

In some examples, including any of the foregoing, the electrolytesolution comprises or is one of the following solvent and fluoride saltcombinations: ECS and LiPF₆, SCN and LiBF₄, and SCN+GLN and LiBF₄.

In some examples, including any of the foregoing, the solvent is acombination of SCN and GLN.

In some examples, including any of the foregoing, the GLN is present at57 wt % of the solution.

In some examples, including any of the foregoing, the solvent has awater content less than 200 ppm, or less than 150 ppm, or less than 100ppm, or less than 60 ppm, or less than 50 ppm, or less than 40 ppm, orless than 30 ppm, or less than 20 ppm, or less than 10 ppm.

In some examples, including any of the foregoing, the temperature isselected from the group consisting of about 20° C., about 25° C., about30° C., about 35° C., about 40° C., about 45° C., about 50° C., about55° C., and about 60° C.

In some examples, including any of the foregoing, the temperature isabout 20° C.

In some examples, including any of the foregoing, the temperature isabout 25° C.

In some examples, including any of the foregoing, the temperature isabout 30° C.

In some examples, including any of the foregoing, the temperature isabout 35° C.

In some examples, including any of the foregoing, the temperature isabout 40° C.

In some examples, including any of the foregoing, the temperature isabout 45° C.

In some examples, including any of the foregoing, the temperature isabout 50° C.

In some examples, including any of the foregoing, the temperature isabout 55° C.

In some examples, including any of the foregoing, the temperature isabout 60° C.

In some examples, including any of the foregoing, the temperature isselected from the group consisting of 20° C., 25° C., and 30° C. In someembodiments, the at least a surface of a sintered thin film garnet issoaked in the electrolyte solution at a temperature that ranges fromabout 20 to about 60° C. In some embodiments, the temperature rangesfrom 20 to 25° C., 20 to 30° C., 20 to 35° C., 20 to 40° C., 20 to 45°C., 20 to 50° C., 25 to 30° C., 25 to 35° C., 25 to 40° C., 30 to 35°C., 30 to 40° C., 35 to 40° C., 35 to 45° C., 35 to 50° C., or 40 to 50°C.

In some embodiments, the temperature is selected from the groupconsisting of about 20° C., about 25° C., about 30° C., about 35° C.,about 40° C., about 45° C., about 50° C., and about 55° C.

In some embodiments, the temperature is selected from the groupconsisting of 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., 50° C.,and 55° C.

In some embodiments, the temperature is 35° C., 40° C., 45° C., 50° C.,55° C., or 60° C.

In some embodiments, the temperature is 60° C.

In some examples, including any of the foregoing, the temperature is 60°C.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by thechemical formula Li_(A)La_(B)Al_(C)M″_(D)Zr_(E)O_(F), wherein 5<A<8,1.5<B<4, 0.1<C<2, 0≤D<2, 1<E<3, 10<F<13, and M″ is selected from thegroup consisting of Mo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, andRb. In some examples, M′ and M″ are the same element selected from thefrom the group consisting of Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce, Hf, Rb,and Ta. However, unless stated explicitly to the contrary, M′ and M″ arenot the same element.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by thechemical formula Li_(x)La₃Zr₂O₁₂+yAl₂O₃, wherein x is from 5.8 to 7.0,and y is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting ofLi_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M″_(D)Ta_(E)O_(F), andLi_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, O≤C<2,O≤D<2; O<E<2, 10<F<14, and wherein M′ and M″ are each, independently,selected from the group consisting of Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce,Hf, Rb, and Ta.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting ofLi_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f) wherein 5<a<7.7; 2<b<4; 0<c<2.5;0<d<2; 0≤e<2, and 10<f<14, and wherein Me″ is a metal selected from thegroup consisting of Nb, Ta, V, W, Mo, and Sb.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting ofLi_(a)La_(b)Zr_(c)Al_(d)O_(f) wherein 5<a<7.7; 2<b<4; 0<c<2.5; 0<d<2;and 10<f<14.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting of Li_(x)La₃Zr₂O₁₂.0.35Al₂O₃wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting of Li_(x)La₃Zr₂O₁₂.0.5Al₂O₃wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting of Li_(x)La₃Zr₂O₁₂.0.65Al₂O₃wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet, prior to step 3, is characterized by aformula selected from the group consisting of Li_(x)La₃Zr₂O₁₂.Al₂O₃wherein 4<x<8.5.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,has a fluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,has an oxyfluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,has both a fluorinated and an oxyfluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,has fluorine or fluoride present at a depth of penetration ranging fromabout 0.5 μm to about 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,has fluorine or fluoride present at a depth of penetration selected fromthe group consisting of about 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm,1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, and 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.6 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.7 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.8 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.9 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.0 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.1 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.2 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.3 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.4 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.5 μm, 0.6 μm,0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, and 1.5μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.6 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.7 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.8 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 0.9 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.0 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.1 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.2 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.3 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.4 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet, after step 4, has fluorineor fluoride present at a depth of penetration of about 1.5 μm.

Without being bound by theory, the depth of penetration can be optimizedand tuned as a function of immersion time in the solution.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,includes fluorine bonded to one or more elements in the lithium-stuffedgarnet.

In some examples, including any of the foregoing, the fluorine is bondedto Al.

In some examples, including any of the foregoing, the fluorine is bondedto Zr.

In some examples, including any of the foregoing, the fluorine is bondedto La.

In some examples, including any of the foregoing, the duration of step 3ranges from 0.1 hours to 24 hours.

In some examples, including any of the foregoing, the duration of step 3ranges from a time selected from the group consisting of 0.5 hours, 1hours, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, and 8hours.

In some examples, including any of the foregoing, the at least onesurface includes a contaminant prior to step 3.

In some examples, including any of the foregoing, the contaminant isselected from the group consisting of hydroxides, peroxides, oxides,carbonates, and combination thereof.

In some examples, including any of the foregoing, the process includesannealing the at least one surface to remove the contaminant prior tostep (3).

In some examples, including any of the foregoing, the process includesannealing methods such as, but not limited to, those annealing methodsdescribed in US 2017/0214084, entitled ANNEALED GARNET ELECTROLYTESEPARATORS, and WO/2017/131676, the entire contents of each of thesepublications are incorporated by reference in their entirety for allpurposes.

In some examples, including any of the foregoing, the process includesannealing the at least one surface to reduce the amount of thecontaminant prior to step (3).

In some examples, including any of the foregoing, the annealing thesurface is in an inert or reducing atmosphere.

In some examples, including any of the foregoing, the at least onesurface is free or substantially free of a contaminant after step 3.

In some examples, including any of the foregoing, the contaminant isLi₂CO₃.

In some examples, including any of the foregoing, the at least onesurface has a lower interfacial resistance after step 4 than before step3.

In some examples, including any of the foregoing, the at least onesurface has a lower ASR after step 4 than before step 3.

In some examples, including any of the foregoing, the at least onesurface has an ASR less than 30 Ωcm² at 45° C. after step 4. In someembodiments, the at least one surface has an area specific resistance(ASR) less than 100 Ωcm² at 45° C. In some embodiments, the ASR is lessthan 90, 80, 70, 60, 50, 40, 30, 20, or 10 Ωcm² at 45° C.

In some embodiments, the at least one surface has an area specificresistance (ASR) less than 30 Ωcm² at 45° C. In some embodiments, the atleast one surface has an area specific resistance (ASR) less than 10Ωcm² at 45° C. In some embodiments, the at least one surface has an areaspecific resistance (ASR) less than 5 Ωcm² at 45° C. In someembodiments, the at least one surface has an area specific resistance(ASR) less than 30 Ωcm² at 25° C. In some embodiments, the at least onesurface has an area specific resistance (ASR) less than 10 Ωcm² at 25°C.

In some embodiments, the at least one surface has an area specificresistance (ASR) substantially as shown in FIG. 3 .

In some embodiments, the at least one surface has an ASR stabilitysubstantially as shown in FIG. 3 . In some embodiments, the at least onesurface has an ASR which is more stable when exposed to ambientconditions when compared to a pristine lithium-stuffed garnet surfaceexposed to the same conditions. In some embodiments, the at least onesurface has an ASR which is more stable when exposed to dry roomconditions when compared to a pristine lithium-stuffed garnet surfaceexposed to the same conditions.

In some examples, including any of the foregoing, the at least onesurface has a lithium ion conductivity of at least 10⁻⁴ S/cm at 45° C.after step 4.

In some examples, including any of the foregoing, the at least onesurface remains free or substantially free of a contaminant in anenvironment of less than −40° C. dew point for up to 3 days.

In some other examples, set forth herein is a sintered lithium-stuffedgarnet thin film made by any process set forth herein.

In some examples, including any of the foregoing, the methods furthercomprises assembling an electrochemical device which includes thesintered thin film lithium-stuffed garnet thin film or pellet.

IV. Surface-Treated Lithium-Stuffed Garnet Electrolytes

In some examples, set forth herein is a sintered lithium-stuffed garnetthin film or pellet including a top surface and bottom surface and abulk therebetween, wherein the top surface or bottom surface, or both,comprise fluorine; wherein the fluorine is incorporated into, or bondedto, the lithium-stuffed garnet. In some examples, the sinteredlithium-stuffed garnet is a thin film. In some examples, the sinteredlithium-stuffed garnet is a pellet.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by the chemical formulaLi_(A)La_(B)Al_(C)M″_(D)Zr_(E)O_(F), wherein 5<A<8, 1.5<B<4, 0.1<C<2,0≤D<2, 1<E<3, 10<F<13, and M″ is selected from the group consisting ofMo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, and Rb.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by the chemical formulaLi_(x)La₃Zr₂O₁₂+yAl₂O₃, wherein x is from 5.8 to 7.0, and y is 0.1, 0.2,0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(A)La_(B)M′_(C)M″_(D)Zr_(E)O_(F),Li_(A)La_(B)M′_(C)M′_(D)Ta_(E)O_(F), andLi_(A)La_(B)M′_(C)M″_(D)Nb_(E)O_(F), wherein 4<A<8.5, 1.5<B<4, O≤C<2,O≤D<2; O<E<2, 10<F<14, and wherein M′ and M″ are each, independently,selected from the group consisting of Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce,Hf, Rb, and Ta. In some examples, M′ and M″ are the same member selectedfrom the from the group consisting of Al, Mo, W, Nb, Sb, Ca, Ba, Sr, Ce,Hf, Rb, and Ta. However, unless stated explicitly to the contrary, M′and M″ are not the same element.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(a)La_(b)Zr_(c)Al_(d)Me″_(e)O_(f)wherein 5<a<7.7; 2<b<4; 0<c<2.5; 0<d<2; 0≤e<2, 10<f<14, and wherein Me″is a metal selected from the group consisting of Nb, Ta, V, W, Mo, andSb.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(a)La_(b)Zr_(c)Al_(d)Of wherein 5<a<7.7;2<b<4; 0<c<2.5; 0<d<2; 10<f<14.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(x)La₃Zr₂O₁₂.0.35Al₂O₃ wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(x)La₃Zr₂O₁₂.0.5Al₂O₃ wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(x)La₃Zr₂O₁₂.0.65Al₂O₃ wherein 4<x<8.5.

In some examples, including any of the foregoing, the lithium-stuffedgarnet thin film or pellet bulk is characterized by a formula selectedfrom the group consisting of Li_(x)La₃Zr₂O₁₂.Al₂O₃ wherein 4<x<8.5.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet has afluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet has anoxyfluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet has both afluorinated and an oxyfluorinated surface.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet has fluorineor fluoride present at a depth of penetration ranging from about 0.5 μmto about 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet has fluorineor fluoride present at a depth of penetration selected from the groupconsisting of about 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1μm, 1.2 μm, 1.3 μm, 1.4 μm, and 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 0.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film, after step 4, hasfluorine or fluoride present at a depth of penetration of about 0.6 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 0.7 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 0.8 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 0.9 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.0 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.1 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.2 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.3 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.4 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film has fluorine or fluoridepresent at a depth of penetration of about 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.5 μm, 0.6 μm, 0.7 μm, 0.8μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, and 1.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.5 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.6 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.7 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.8 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 0.9 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.0 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.1 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.2 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.3 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.4 μm.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet pellet has fluorine or fluoridepresent at a depth of penetration of about 1.5 μm.

Without being bound by theory, the depth of penetration can be optimizedand tuned as a function of immersion time in the solution.

In some examples, including any of the foregoing, the at least onesurface of the lithium-stuffed garnet thin film or pellet includesfluorine bonded to one or more elements in the lithium-stuffed garnet.

In some examples, including any of the foregoing, the fluorine is bondedto Al.

In some examples, including any of the foregoing, the fluorine is bondedto Zr.

In some examples, including any of the foregoing, the fluorine is bondedto La.

In some examples, including any of the foregoing, the bulk has less than0.5 atomic percent fluorine as measured by XPS.

In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 1 nm to 10 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of about 1 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 2 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 3 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 4 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 5 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 6 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 7 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 8 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 9 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 10 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 11 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 12 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 13 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 14 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 15 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 20 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 25 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 30 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 35 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 40 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 45 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 50 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 55 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 60 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 65 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 70 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 75 nm. In some examples, including any of theforegoing, the top or bottom surface In some examples, including any ofthe foregoing, the top or bottom surface has a thickness of about 85 nm.In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 80 nm. has a thickness of about 90 nm.In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 95 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of about 100nm. In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 200 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of about 300nm. In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 400 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of about 500nm. In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 600 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of about 700nm. In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 800 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of about 900nm. In some examples, including any of the foregoing, the top or bottomsurface has a thickness of about 1000 nm. In some examples, includingany of the foregoing, the top or bottom surface has a thickness of about2 μm. In some examples, including any of the foregoing, the top orbottom surface has a thickness of about 3 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of about 4 μm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 5 μm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 6 μm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 7 μm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 8 μm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of about 9 μm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of about 10 μm.

In some examples, including any of the foregoing, the top or bottomsurface has a thickness of 1 nm to 10 μm. In some examples, includingany of the foregoing, the top or bottom surface has a thickness of 1 nm.In some examples, including any of the foregoing, the top or bottomsurface has a thickness of 2 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of 3 nm. In someexamples, including any of the foregoing, the top or bottom surface hasa thickness of 4 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 5 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 6 nm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 7 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 8 nm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 9 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 10 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 11 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 12 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 13 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 14 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 15 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 20 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 25 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 30 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 35 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 40 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 45 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 50 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 55 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 60 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 65 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 70 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 75 nm. In some examples,including any of the foregoing, the top or bottom surface In someexamples, including any of the foregoing, the top or bottom surface hasa thickness of 85 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 80 nm. has a thickness of90 nm. In some examples, including any of the foregoing, the top orbottom surface has a thickness of 95 nm. In some examples, including anyof the foregoing, the top or bottom surface has a thickness of 100 nm.In some examples, including any of the foregoing, the top or bottomsurface has a thickness of 200 nm. In some examples, including any ofthe foregoing, the top or bottom surface has a thickness of 300 nm. Insome examples, including any of the foregoing, the top or bottom surfacehas a thickness of 400 nm. In some examples, including any of theforegoing, the top or bottom surface has a thickness of 500 nm. In someexamples, including any of the foregoing, the top or bottom surface hasa thickness of 600 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 700 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 800 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 900 nm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 1000 nm. In some examples, including any of the foregoing,the top or bottom surface has a thickness of 2 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 3 μm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 4 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 5 μm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 6 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 7 μm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 8 μm. In some examples,including any of the foregoing, the top or bottom surface has athickness of 9 μm. In some examples, including any of the foregoing, thetop or bottom surface has a thickness of 10 μm.

In some examples, including any of the foregoing, the top and bottomsurface has a thickness of about 1 nm to 10 μm.

In some examples, including any of the foregoing, the sinteredlithium-stuffed garnet is a thin film.

In some examples, including any of the foregoing, the sinteredlithium-stuffed garnet is a pellet.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day to 5 days.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day to 365 days.

In some examples, including any of the foregoing, the contaminant isselected from the group consisting of hydroxides, peroxides, oxides,carbonates, and combination thereof.

In some examples, including any of the foregoing, the surface comprisingfluorine is stable in ambient environment up to 3 days. In someembodiments, the surface comprising fluorine has less than 10% ofsurface Li₂CO₃ as measured by XPS after exposure to room temperature anda dew point of less than −10° C. for 3 days.

In some examples, including any of the foregoing, the contaminant isLi₂CO₃.

In some examples, including any of the foregoing, the top or bottomsurface, or both, includes less than 10 atomic % Li₂CO₃ as measured byXPS after exposure to room temperature and a dew point of less than −10°C. for 3 days.

In some examples, including any of the foregoing, the top or bottomsurface, or both, has an area specific resistance (ASR) less than 100Ωcm² at 45° C.

In some examples, including any of the foregoing, the top or bottomsurface, or both, has an area specific resistance (ASR) less than 30Ωcm² at 45° C.

In some examples, including any of the foregoing, the top or bottomsurface, or both, has an area specific resistance (ASR) less than 10Ωcm² at 25° C.

In some examples, including any of the foregoing, the top or bottomsurface, or both, has a lithium ion conductivity of at least 10⁻⁴ S/cmat 45° C.

In some examples, including any of the foregoing, the top or bottomsurface, or both, includes trace amounts of contaminants.

In some examples, including any of the foregoing, set forth herein is asintered thin film lithium-stuffed garnet comprising a top surface andbottom surface and a bulk therebetween, wherein the top surface orbottom surface, or both, comprise fluorine which is incorporated into,or bonded to, the garnet; wherein the bulk has less than 0.5 atomicpercent (at %) fluorine as measured by XPS. In some examples, the bulkhas 0.4 at %, 0.3 at %, 0.2 at %, or 0.1 at % fluorine as measured byXPS. In some examples, the bulk has less than 0.4 at %, 0.3 at %, 0.2 at%, or 0.1 at % fluorine as measured by XPS.

In some examples, including any of the foregoing, of the sintered thinfilm lithium-stuffed garnet, the top surface or bottom surface, or both,are free or substantially free of a contaminant.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day to 5 days.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day to 1 year.

In some examples, including any of the foregoing, the contaminant isselected from the group consisting of hydroxides, peroxides, oxides,carbonates, and combinations thereof.

In some examples, including any of the foregoing, the surface comprisingfluorine has an area specific resistance (ASR) less than 100 Ωcm² at 45°C. In some examples, the surface comprising fluorine has an ASR lessthan 90, 80, 70, 60, 50, 40, 30, 20, or 10 Ωcm² at 45° C.

In some examples, including any of the foregoing, the surface comprisingfluorine has an area specific resistance (ASR) less than 30 Ωcm² at 45°C. In some examples, the surface comprising fluorine has an areaspecific resistance (ASR) less than 10 Ωcm² at 45° C. In some examples,the surface comprising fluorine has an area specific resistance (ASR)less than 5 Ωcm² at 45° C. In some examples, the surface comprisingfluorine has an area specific resistance (ASR) less than 30 Ωcm² at 25°C. In some examples, the surface comprising fluorine has an areaspecific resistance (ASR) less than 10 Ωcm² at 25° C.

In some examples, including any of the foregoing, the surface comprisingfluorine has an area specific resistance (ASR) as shown in FIG. 3 . Insome examples, including any of the foregoing, the surface comprisingfluorine has an area specific resistance (ASR) stability as shown inFIG. 3 . In some examples, the surface comprising fluorine has an areaspecific resistance (ASR) less than 10 Ωcm² at 25° C.

In some examples, including any of the foregoing, the surface comprisingfluorine has a lithium ion conductivity of at least 10⁻⁴ S/cm at 45° C.

In some examples, including any of the foregoing, the top surface orbottom surface, or both, are fluorinated and comprise trace amounts ofcontaminants. In some examples, the trace amount of contaminant is lessthan 1.0 wt %, 0.9 wt %, 0.8 wt %, 0.7 wt %, 0.6 wt %, 0.5 wt %, 0.4 wt%, 0.3 wt %, 0.2 wt %, or 0.1 wt %.

V. Method of Using a Surface-Treated Solid-State Electrolyte

In some examples, set forth herein is a method including, providing asintered thin film lithium-stuffed garnet film or pellet set forthherein; exposing the sintered thin film lithium-stuffed garnet thin filmor pellet to ambient conditions; and measuring the ASR of the sinteredthin film lithium-stuffed garnet. In some examples, the measuring occursin a dry room. In some examples, the measuring is accomplished byelectrical impedance spectroscopy (EIS).

In some examples, including any of the foregoing, the ASR does not varyby more than 10% over a surface area of at least 10 mm².

In some examples, including any of the foregoing, the ASR does not varyby more than 10% as a function of time for at least 1 day.

In some examples, including any of the foregoing, the ASR does not varyby more than 10% as a function of time for at least 365 days.

In some examples, including any of the foregoing, the ASR of thesintered thin film lithium-stuffed garnet after exposure to ambientconditions did not increase by more than 10%.

VI. Devices and Vehicles

In some examples, set forth herein is an electrochemical deviceincluding a sintered lithium-stuffed garnet thin film set forth herein.

In some examples, set forth herein is an electric vehicle including anelectrochemical device set forth herein.

In some examples, set forth herein is an electric vehicle including anelectrochemical device which includes a sintered lithium-stuffed garnetthin film set forth herein.

In some examples, set forth herein is an electric vehicle which includesa sintered lithium-stuffed garnet thin film set forth herein.

EXAMPLES

X-ray photoelectron spectroscopy (XPS) measurements were performed on aThermo Scientific Model K-Alpha 1 XPS instrument. Monochromatic and AlX-ray source with X-ray energy of 1486.6 eV was used with a spot size of400 μm. The base pressure when the measurement was conducted is 2*10⁻⁹mbar or below.

Fluorine-19 (¹⁹F) solid-state NMR measurements were performed at 25° C.on a Bruker NMR Spectrometer operating at 470.5 MHz ¹⁹F NMR frequency.The MAS (Magic Angle Spinning) at high spinning speed (up to 30 kHz) wasused to reduce NMR line widths. The chemical shifts were referenced withrespect to trichlorofluoromethane (CFC₁₃) with the fluorine peak set to0 ppm.

Example 1 Electrolyte Solution Cleaning Effect on Lithium-Stuffed GarnetThin Film Surface

This Example demonstrates a process for removing surface contaminantsfrom the surface of LLZO thin films.

LLZO thin films were prepared as follows. Certain procedures in U.S.application Ser. No. 15/007,908 filed on Jan. 27, 2016 and published asU.S. 2017/0214048 on Jul. 27, 2017, entitled ANNEALED GARNET ELECTROLYTESEPARATORS, the entire contents of which are herein incorporated byreference in their entirety for all purposes, were incorporated.

Lithium-Stuffed Garnet Powder was prepared. Calcined lithium-stuffedgarnet powder was produced by the following series of steps. First,lithium hydroxide (LiOH), aluminum nitrate [Al(NO₃)₃9H₂O], zirconia(ZrO₂), and lanthanum oxide (La₂O₃) were massed (i.e., weighed) andmixed into a combination wherein the molar ratio of the constituentelements was Li_(7.1)Zr₂La₃O₁₂+0.5Al₂O₃. This combination was mixed andmilled, using wet-milling techniques and ZrO₂ milling media, until thecombination had a d₅₀ particle size of 100 nm-5 μm. Also included withthe milling media was a menhaden fish oil dispersant. The milledcombination of reactants was separated from the milling media aftermilling. The d₅₀ particle size of the milled reactants was assessed. Theseparated milled reactants was then placed in an alumina crucible andcalcined at about nine-hundred degrees Celsius (900° C.) forapproximately six (6) hours in an oven with a controlled oxidizingatmosphere in contact with the calcining reactants. The calcinationprocess burned and/or combusted residual solvents as well as thedispersant, binder, and surfactant. The calcination caused the inorganicreactants to react to form the lithium-stuffed garnet. The calcinedproduct was removed from the alumina crucibles after it cooled to roomtemperature. The product is characterized by a variety of analyticaltechniques, including x-ray powder diffraction (XRD) and scanningelectron microscopy. This product is referred to as calcinedlithium-stuffed garnet and has an empirical formula of approximately wasLi_(7.1)Zr₂La₃O₁₂+0.5Al₂O₃.

The milled and calcined product were then mixed with a plasticizer(S160), a binder (B72). Alternatively, an acrylic, polyvinylbuturate(PVB), or polyvinylacetate (PVA) may be used. The solvent was a mixtureof dimethyl ether/tetrahydrofuran (DME/THF). The organic componentsconstituted 10-20 weight percent of the slurry. The remainder of theslurry was the solid calcined lithium-stuffed garnet having theempirical formula of approximately Li_(7.1)Zr₂La₃O₁₂+0.5Al₂O₃.

The slurry mixture was then tape cast using a doctor blade setting of 20μm-400 μm to produce 10 μm-200 μm thin films of calcined but unsinteredlithium-stuffed garnet in combination with surfactants, binders,plasticizers, and dispersants.

The tape cast thin films were allowed to dry. These dry calcined butunsintered thin films are referred to as green films.

The green films were placed between garnet ceramic setter plates andcalcined in an oven filled with an Argon:H₂O mixture followed by anArgon:H₂ mixture and heated to 1200° C. for six (6) hours. Setter plateswere used as substantially set forth in International PCT PatentApplication No. PCT/US16/27886, filed Apr. 15, 2017, entitled LITHIUMSTUFFED GARNET SETTER PLATES FOR SOLID ELECTROLYTE FABRICATION, theentire contents of which are herein incorporated by reference in theirentirety for all purposes. The setter plates were made primarily oflithium-stuffed garnet formed into a setter. In some samples, the greenfilms were sintered at 1125° C. for 6 hours in an oven with a controlledatmosphere in contact with the calcining reactants.

The sintered films were then exposed to air for 24-48 hours at roomtemperature, which resulted in the formation of Li₂CO₃ on the surface ofthe thin films. The sintered films with Li₂CO₃ on their surface werethen placed in either a dry room or glove box for further processingwith the solutions in Table 1.

The solutions in Table 1 were prepared.

TABLE 1 Combination of electrolytic solution (solution + salt) andcleaning effect Solvent system Salt (Concentration) cleaning effectobserved Succinonitrile (SCN) LiBF₄ (12 mol %) Yes SCN + GLN LiBF₄ (12mol %) Yes ECS LiPF₆ (1M) Yes ECS LiBF₄ (1M) Yes EC-EMC LiPF₆ (1M)Minimal *Glutaronitrile (GLN); ethylene carbonate and sulfolane (ECS)and ethylene carbonate-ethyl-methyl carbonate (EC-EMC).

The sintered films were individually soaked in the solutions in Table 1at 60° C. for 12 hours. After soaking, the films were removed anddried/wiped with a Kimwipe. Then the sintered films were rinsed withisopropanol (i.e., isopropyl alcohol or IPA) and then dried in the dryroom or glove box (GB).

Dry room condition were −40° C. humidity and RT (room temperature). GBconditions were argon with a O₂ partial pressure of less than 10 ppm anda H₂O partial pressure of 0.1 ppm.

A non-soaked sintered film was used as a control.

The sintered films, with and without exposure to the solutions in Table1, were analyzed by x-ray photoelectron spectroscopy (XPS) scan between0 and 1000 eV. The binding energy of each film was measured. The resultis shown in FIG. 1 .

FIG. 1 shows the binding energy data of the surfaces of the films havingbeen treated as follows:

-   -   (a) Non-soaked control,    -   (b) Soaked in ECS LiPF₆ electrolyte solution,    -   (c) Soaked in SCN LiBF₄ electrolyte solution,    -   (d) Soaked in dinitrile (SCN+GLN) LiBF₄ electrolyte solution.

The data in FIG. 1 demonstrates that the Li₂CO₃ on the surface of LLZOcan be removed by exposure to the solutions in Table 1.

FIG. 1 shows the results of treating sintered lithium-stuffed garnetwith solutions that include either LiPF₆ or LiBF₄ fluoride salts andthat include ECS, SCN solvents or combinations thereof. FIG. 1 shows, in(a), CO₃ binding energy peak at 289.8 eV which is assigned to carbonfrom Li₂CO₃. This peak disappears in the treated samples b-d. As carbonof the carbonate peak diminishes, lanthanum (La 4d around 102 eV),Zirconia (3d around 182 eV), and Fluorine (around 691 eV) peaks wereobserved.

Example 2—Exposure Study of Clean/Soaked Films

LLZO thin films were prepared according to Example 1.

One sintered thin film was immersed in an electrolyte solution of SCNand LiBF₄ (12 mol %) at 60° C. for 12 hours. This film is referred to asthe treated film.

One sintered thin film was left untreated.

Both the treated film sample and the untreated film sample were storedin a dry room as well as in a glove box for 0, 3, and 8 hours. TheCO₃/Zr peak area ratio for each film was measured by XPS as a functionof exposure time in either the dry room or in the glove box. The resultfor the treated is shown in FIG. 2 . The results for the treated anduntreated samples are summarized in the following table:

CO₃/Zr peak area Time Treatment Stored in dry room for: 0 h ~0 Stored indry room for: 3 h 0.04 Stored in dry room for: 8 h 0.08 Stored in airfor: 0 h ~0 Stored in air for: 3 h 8 Stored in air for: 8 h 20

No treatment (i.e., CO₃/Zr peak area Time untreated) Stored in dry roomfor: 0 h ~0 Stored in dry room for: 5 min 12 Stored in dry room for:1.25 h 18 Stored in dry room for: 24 h 22

FIG. 2 shows an exposure study of untreated and treated samples exposedin argon and dry room environments for 0, 3 and 8 hours. The resultshows that the treated surface is stable for at least 30 hours in dryroom environments, i.e., room temperature and −40° C. dew point, whereasthe untreated surface forms lithium carbonate during the exposure time.Soaking the sintered thin film in the solution in this Examplepassivated the surface against forming lithium carbonate.

Example 3—ASR Study of a Full Cell Using the Treated Samples fromExamples 1 and 2

Electrochemical cells were assembled in which the treated samples fromExamples 1 and 2 were used as the solid-state electrolyte separator, asillustrated in FIG. 6 .

FIG. 6 shows an illustration of a full cell architecture containing agel bonding layer (1M ECS/LiPF₆ in contact with the positive electrodeand garnet separator) between the solid-state electrolyte separator (80μm thick) and a solid-state cathode (⅔ NCA, ⅓ LSTPS catholyte, <5% dowchemical EG8200/Carbon 1.5 wt %/0.5% wt %; approximately 150 μm inthickness. In the figure, 10 is a solid-state cathode, 20 is a bondinglayer (not drawn to scale), which is between the treated thin film, 30,and a lithium metal anode, 40.

The ASR of a full cell using the treated sample was tested. AGalvanostatic Intermittent Titration Technique (GITT) test was performedat 45° C. for charging between 3.7-4.3V. The charge pulses were at aC/10 rate for 30 min and the rests were 3 minutes. The test instrumentwas Arbin potentiostat. The ASR is plotted versus the rest voltage atthe end of the rest period. Area-specific resistance was calculated bythe formula, ASR_(dc)=ΔV/j, where j is the applied current densityduring the charge pulse and ΔV is the voltage difference between theloaded voltage and the resting voltage. The results are shown in FIG. 3.

In FIG. 3 , four repeat samples (corresponding to the four plots in FIG.3 ) were prepared and tested in which the sintered thin film garnet wastreated with SCN+GLN and LiBF₄ (12 mol %). FIG. 3 shows the ASR testingresults for full cells using these treated garnets. It was observed thatthey repeatedly have a low full cell ASR, of less than 30 Ωcm² at 45° C.The cathode, anode interface, and bulk separator account for 15-25 Ωcm²of the total. The separator-cathode interface has a small contributionto the total resistance.

Example 4—Surface Concentration of Fluorine

This Example shows the depth of penetration into the surface of asintered LLZO thin film for Fluorine (F) from the solutions in which thethin film is immersed and treated.

Fluorine atomic % was determined by XPS for the sample in Example 1 thatwas soaked in succinonitrile (SCN) and LiBF₄ (12 mol %) for 8 hours andat 70° C. The results are summarized below:

Element Atomic % Level Zr3d % La4d % O1s % F1s % Li1s % Level 0 2.9 427.2 29.03 36.87 (Surface)

Based on the results herein, the depth of penetration into the surfaceof a sintered LLZO thin film for F from the solutions in which the thinfilm is immersed and treated was determined to be 1 μm. These resultsare shown in FIG. 4 . FIG. 4 also shows the depth of penetration of Zrand O in the surface of the sintered LLZO thin film.

Example 5—NMR Measurement Showing F Incorporation in the Lattice of LLZORather than as Another Species (e.g., LIF)

The sample from Example 4 was analyzed by ¹⁹F solid-state NMR.

The results are shown in FIG. 5 .

The NMR results show that F is incorporated into the lattice of LLZOrather than into another species, e.g. LiF.

The fluoride NMR shows shift of the peaks. The bottom spectrum is of dryLiBF₄. The spectrum is referenced at zero with CFCl₃. The top spectrumis that of the sintered LLZO thin film that was treated with SCN/LiBF₄.The fluorine peak has shifted compared to the pure LiBF₄ peak becausethe BF₄ has reacted with the garnet surface and changed the chemicalenvironment.

The embodiments and examples described above are intended to be merelyillustrative and non-limiting. Those skilled in the art will recognizeor will be able to ascertain using no more than routine experimentation,numerous equivalents of specific compounds, materials and procedures.All such equivalents are considered to be within the scope and areencompassed by the appended claims.

The invention claimed is:
 1. A process for making a sinteredlithium-stuffed garnet thin film or pellet, comprising (1) providing asolution comprising a fluoride salt and a solvent; (2) providing asintered lithium-stuffed garnet thin film or pellet; (3) immersing atleast one surface of the sintered lithium-stuffed garnet thin film orpellet in the solution at a temperature between, or equal to, 0° C. and60° C.; and (4) removing the at least one surface of the sinteredlithium-stuffed garnet thin film from the solution.
 2. The process ofclaim 1, wherein fluoride salt is selected from the group consisting ofLiPF₆, lithium bis(perfluoroethanesulfonyl)imide (LIBETI),bis(trifluoromethane)sulfonimide lithium salt (LiTFSI), LiBF₄, LiAsF₆,lithium bis(fluorosulfonyl)imide (LiFSI), and combinations thereof. 3.The process of claim 1, wherein the concentration of fluoride salt isabout 0.5 M to about 1.5 M.
 4. The process of claim 1, wherein thesolvent is selected from the group consisting of ethylene carbonate(EC), diethylene carbonate, dimethyl carbonate (DMC), ethyl-methylcarbonate (EMC), propylmethyl carbonate, nitroethyl carbonate, propylenecarbonate (PC), diethyl carbonate (DEC), methyl propyl carbonate (MPC),2,5-dioxahexanedioic acid dimethyl ester, tetrahydrofuran (THF),γ-butyrolactone (GBL), fluoroethylene carbonate (FEC), fluoromethylethylene carbonate (FMEC), trifluoroethyl methyl carbonate (F-EMC),fluorinated3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane/1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane(F-EPE), fluorinated cyclic carbonate (F-AEC), dioxolane,prop-1-ene-1,3-sultone (PES), sulfolane, acetonitrile (ACN),succinonitrile (SCN), pimelonitrile, suberonitrile, propionitrile,propanedinitrile, glutaronitrile (GLN), adiponitrile (ADN),hexanedinitrile, pentanedinitrile, acetophenone, isophorone,benzonitrile, ethyl propionate, methyl propionate, methylenemethanedisulfonate, dimethyl sulfate, dimethyl sulfoxide (DMSO), ethylacetate, methyl butyrate, dimethyl ether (DME), diethyl ether,dioxolane, gamma butyl-lactone, methyl benzoate,2-methyl-5-oxooxolane-2-carbonitrile, and combinations thereof.
 5. Theprocess of claim 4, wherein the solvent is selected from the groupconsisting of succinonitrile (SCN), glutaronitile (GLN), sulfolane,ethylene carbonate (EC), ethyl-methyl carbonate (EMC), and combinationsthereof.
 6. The process of claim 5, wherein the solvent has a watercontent less than 200 ppm, or less than 150 ppm, or less than 100 ppm,or less than 60 ppm, or less than 50 ppm, or less than 40 ppm, or lessthan 30 ppm, or less than 20 ppm, or less than 10 ppm.
 7. The process ofclaim 1, wherein the lithium-stuffed garnet thin film or pellet, priorto step 3, is characterized by the chemical formulaLi_(A)La_(B)Al_(C)M″_(D)Zr_(E)O_(F), wherein 5<A<8, 1.5<B<4, 0.1<C<2,0≤D<2, 1<E<3, 10<F<13, and M″ is selected from the group consisting ofMo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, and Rb.
 8. The process ofclaim 1, wherein the at least one surface of the lithium-stuffed garnetthin film or pellet, after step 4, has a fluorinated surface.
 9. Theprocess of claim 8, wherein the at least one surface of thelithium-stuffed garnet thin film or pellet, after step 4, has fluorineor fluoride present at a depth of penetration ranging from about 0.5 μmto about 1.5 μm.
 10. The process of claim 8, wherein the at least onesurface of the lithium-stuffed garnet thin film or pellet, after step 4,comprises fluorine bonded to one or more elements in the lithium-stuffedgarnet.
 11. The process of claim 1, wherein the at least one surface isfree or substantially free of a contaminant after step
 3. 12. Theprocess of claim 11, wherein the contaminant is Li₂CO₃.
 13. A sinteredlithium-stuffed garnet thin film or pellet comprising: a top surface andbottom surface and a bulk therebetween, wherein the top surface orbottom surface, or both, comprise fluorine; wherein the fluorine isincorporated into, or bonded to, the lithium-stuffed garnet.
 14. Thesintered lithium-stuffed garnet thin film or pellet of claim 13, whereinthe lithium-stuffed garnet thin film or pellet bulk is characterized bythe chemical formula Li_(A)La_(B)Al_(C)M″_(D)Zr_(E)O_(F), wherein 5<A<8,1.5<B<4, 0.1<C<2, 0≤D<2, 1<E<3, 10<F<13, and M″ is selected from thegroup consisting of Mo, W, Nb, Y, Ta, Ga, Sb, Ca, Ba, Sr, Ce, Hf, andRb.
 15. The sintered lithium-stuffed garnet thin film or pellet of claim13, wherein the at least one surface of the lithium-stuffed garnet thinfilm or pellet has a fluorinated surface.
 16. The sinteredlithium-stuffed garnet thin film or pellet of claim 15, wherein the atleast one surface of the lithium-stuffed garnet thin film or pellet hasfluorine or fluoride present at a depth of penetration ranging fromabout 0.5 μm to about 1.5 μm.
 17. The sintered lithium-stuffed garnetthin film or pellet of claim 16, wherein the at least one surface of thelithium-stuffed garnet thin film or pellet comprises fluorine bonded toone or more elements in the lithium-stuffed garnet.
 18. The sinteredlithium-stuffed garnet thin film or pellet of claim 14, wherein thesintered lithium-stuffed garnet is a thin film.
 19. The sintered thinfilm lithium-stuffed garnet of claim 13, wherein the top surface orbottom surface, or both, remain free or substantially free of acontaminant after exposure to ambient conditions for 1 day to 365 days.20. The sintered thin film lithium-stuffed garnet of claim 19, whereinthe contaminant is selected from the group consisting of hydroxides,peroxides, oxides, carbonates, and combination thereof.
 21. The sinteredthin film lithium-stuffed garnet of claim 20, wherein the contaminant isLi₂CO₃.